Fluid purification systems are used in many different types of applications. Water purification techniques are widely used in both open and closed-loop water systems to reduce levels of contaminants and to maintain conditions suitable for habitation, for example washing and bathing, leisure activities such as swimming. Perhaps most important, such systems are used to create potable water from various water sources which may contain different kinds of organic and inorganic contaminants that are unsuitable for human consumption, or even dangerous.
Both open- and closed-loop water systems, such as aqueduct networks, water towers, ice machines and particularly hot water systems such as boilers, vapour humidifiers and the like, are prone to calcification, scale formation and contamination by many types of biological contaminants. The nature and extent of these problems varies depending upon the water chemistry and the type of water system. In many cases, a large portion of the cost of maintaining a water system is devoted to the elimination of minerals and contamination caused by microbiological pollutants such as bacteria, endotoxins, moulds, parasites, fungus and viruses.
The purification of large volumes of water by conventional techniques has conventionally been costly and problematic. Chemical treatments tend to have undesirable side effects, and can actually be harmful if precise conditions are not maintained. Mechanical filtration is probably the most common method of water purification, but it is substantially limited both in terms of the rate at which water can be purified and the useful life of the filter used in the system.
Reverse osmosis filtration is one of the most effective filtration techniques. In a typical reverse osmosis filtration system, water is forced through a semi-permeable membrane to extract pollutants and contaminants. Reverse osmosis systems provide an extremely effective level of filtration initially, but this tends to degrade quickly as the membrane deteriorates and becomes clogged with contaminant particles.
In water treatment systems the filter membrane is subject not only to clogging by fine particles, but also tends to become positively charged as electrons are shed into the passing water, and the charged membrane actually attracts and holds neutral particles such as calcium carbonate, exacerbating clogging of the membrane. Moreover, reverse osmosis filter membranes require continual replacement as a result of constant wear and tear from undesirable elements, for example some types of inorganic contaminants, such as calcium carbonate, which coalesce in water systems to form sharp, needle-like structures that pierce and erode the filter membrane. This significantly limits the life of the membrane and results in a slowly deteriorating output water quality and filtration rate.
Reverse osmosis filter membranes are so sensitive that in many environments, once the efficiency of the filter membrane drops by as little as 2% the membrane must be replaced. Thus, reverse osmosis filter membranes must be replaced on a regular basis, which is very costly.
It is known to treat and/or pre-treat fluids such as water with electrostatic fields, to eliminate biological pollutants and reduce calcification and scaling in water circulation systems. However, there has previously been no system capable of efficiently and effectively treating fluids such as water in large volumes, or for treating fluids such as water for prolonged intervals without the need for continuous maintenance and replacement of filter membranes.
It would accordingly be advantageous to provide a system capable of reducing or eliminating mineralization and biological contamination in fluid circulation and distribution systems. It would further be advantageous to provide a system which effectively pre-treats a fluid prior to filtration, to reduce the harmful effects of contaminants on the filter membrane and thus prolong the useful life of the membrane.